Method of recovery of potassium and magnesium salts from natural brines and calcareous muds



Aug., 19 1924. J. L. SILSBEE METHOD 0R RECOVERY oF PoTAssIUM AND MAGNBSIUM sALTs FROM NATURAL BRINES `AND cALcAREoUs MUDS Filed July 27. 1920 L LDHR @,Nzfl

-satema Aug. 19,1924'. Y

* 'UNITED vsir-Arias,

JOSEPH SILSBE, `F SALT LAKE CITY, UTAH.

MErHoD or 'RECOVERY and State of Utah, have invented certain new and useful Improvements in Methods of Recovery of Potassium and Ma Salts from Natural B'rines and Ca careous Muds; 'and I do hereby declare the following to' be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains tov make and use the same.

v This invention relates particularly to a method of treating certain natural deposits found in the desert regions of the Western States for the recovery of calcium sulphateand the chlorides of sodium, potassium and calcium, and carbonates of magnesium and potassium and the oxide of magnesium. I

The natural deposits referred to consist of natu-ral brine and a calcareous marl or mud carrying a certain amount of water soluble and water insoluble potassium.

The deposits or mud flats in which the brine and mud are found are usually .fiat desert areas, the mud surface of whichis usually dry, but beneath the surface, brine is found? i The brine contains potassium, sodium and magnesium chlorides lin varying proportions and degrees Aof concentration, but the sodi.- um chloride is usually present in the brine in'1a r,g;e'excess.` A certain amount lof sulphate is also frequently present.

Calcium carbonate is found in the heavy plastic brine-saturated mud. The mud also contains water-,insoluble potassium, usually in loosechemical combination with the mud ormarl. No practical commercial method of recovering this insoluble potassium from the mud has heretofore been devised, so far as I am aware and is herein described 'for the first time. -5

It is one of the principal objects of my present invention to provide a simple and relatively inexpensive ,method by .whichthevalues contained inthe brine and the values I contained in the mud can be recovered, advantage being taken of the various chemical 'constituents of each vto enablethe values to be recovered .from both.

A The recovery of sodium chloride and pol.

or ro'rAssruM AND MAGuEsIU'M sALTs snor: NATURAL BnrNEs AND cAncAnEous Mons.

P--A'IENTg OFFICE.

Application filed July 27, '1920. Serial No. 399,388.

tassium chloride from brines obtained from deposits of a similar nature has already been fully set forth in my co-pending applications, Serial Nos.V 332,441 and my PatentNo. 1,353,283, to which reference may be had, and of which the present application is a continuation in part.

In those ap lications, the sodium chloride was described) as being obtained by solar evaporation and mixed potassium chloride and sodium chloride salts were obtained by a second or further solar evaporation. This mixed salt, containing approximately twenty-ive per cent KCl constituted the 'chief source of the crude material from which refined potassium chloride was produced. The solar production of the .crude mixed salt leaves a by-product liquor containing a large amount of magnesium chloride which was recovered by evaporation.

This magnesium chloride mother liquor comprises a" part of the raw material that is used in my present method.

The methods referred to, however, made no use of the brine-impregnated calcareous mud which underlies the surface deposits for an unknown depth, and are, to a certain extent, limited to use withbrines containing a relativel7 small proportion of sulf phate. Y l

yThis mud. is extremely plasticv and is usually impregnated with brine. It frequently contains` about per cent water- Percent. Calcium carbonate i- 72 Magnesium carbonate 6 Iron and aluminum oxidei 1 4 Silica '13 Thel original moist mud has been foun'd to contain 6 Aper cent KZC `(equivalent to about l() per cent potassiumchloride) partly in a water-soluble and partly in a water-insoluble form.

The above approximate analysis does not show the *determination of KZC, since`the KZO content of the mud varies at various-V locations andat different depths. The water insoluble pota'sh contents of the mud may under certain conditions be entirely washed out.

My present invention employs the methods of the above named applications for the recovery of sodium and potassium chloride from the brine, and the production of the said magnesium chloride bfyLfl-ptroduct liquor.

-@It also includes certain her steps by which the calcareous mud combined with the products obtained from the magnesium chloride liquor and a part of the potassium chloride produced by the previously described proce may be ,converted into a number of additional and valuable by-products, namely, magnesium oxide, magnesium carbonate, potassium carbonate, potassium bicarbonate, calcium chloride and calcium sulphate.

The present method contemplates the utilization of practically all of the values not only in the brine, but also in the marl or mud, and accomplishes this'y result without the necessity of u any Vre-agents other than those resulting om the various steps of the process itself.

Although the recovery of potassium salts from the above described mud might not by e itself be of commercial importance in the development of the potash industry, I have found it to be a fact that the recovery of the potassium contents of the mud and of the brine, andthe production of calcium chloride liquor for use in ridding the potassium-bearing brine of sulphates, as well as the production of carbon dioxide gas for use in producing magnesium carbonate and potassium carbonate, is a process that is not only novel, but commerciall practicable. The treatment converts a therto practically useless natural deposit into a series of commercially valuable products.

My method is not necessaril confined to the employment of the spec' c muds and brines of the natural deposits referred to for it is obvious that the same method of recovering the carbonates of magnesium and potassium and the oxide of magnesium could be applied if limestone instead of marl were employed.

I will, however, for purpose of illustration, describe my method as applied to the brine and to mud havingthe c aracteristics of the deposits referred to.

The drawing is a diagrammatic iiow sheet showing the various steps of the process for completely recovering the values contained in the brine and the mud.

Solar vats, as 1, 2, 3 are provided for treating' the brine to recover a mixed salt of sodium and potassium chloride, or if desired, to recover carnalite, either case leaving a magnesium chloride mother liquor,

j as in vat'.

The details'of this solar brine treatment and the subsequent refining of the `solar salts Y from a' fuel supp are fully set forth the applications preand filtering and storing potassium chloride,l

as at 8 and 9.

The solvent liquor used in dissolver 5 is hot; having been heated, as at 10. The liquor is obtained from vthe brine supply, which may be either a ditch, as indicated at the right in the diagram, or, if the brine contains sulphate, the solvent liquor may be drawn from a solar vat, as 35, the purpose of which will be described later.

On the way from the brine supply to the dissolver 5, the solvent liquor ma be first heated, as at 11, and used to was sodium chloride crystals in Ithe salt washer l2. The sodium chloride, after liltering at 13, is delivered to storage 14.

Solar evaporation may be employed in vvat 3 to concentrate the mother liquor from rated, as at 16. The'cool magnesium .chloride liquor may be added to the magnesium chloride liquor from vat 4, which is a byproduct of the solar evaporation and constitutes the main source of supply of the magnesium vchloride liquor used in my method of treating the marl orlmud.

. ln my present process the said magnesium chloride liquor is mixed, as at 1'?, with magnesium oxide which is preferably obtained from a later stepV in the process. The liquor is made in such proportions as to obtain a solid consisting essentially of magnesiumoxychloride. This solid is roasted in a kiln 18 at a tem erature of six-hundred to sevenhundredy degrees centigrade, preferably by the' use of gas or powdered fuel i9, the resulting products being chieiiy hydrochloric acid gas and magnesium oxide. Part of the magnesium oxide may be stored, as at 20, and marketed and the remainder is divided between the amount which, as noted above, was mixed With'the magnesium chloride liquor in 17, and an additional amount to 'be used in a later step of the process for the production ofpotassium and magnesium carbonate.

The hydrochloric acid gas produced in the kiln' is then brought' into intimate contact, as in gas towers V21. and 22, with a supply of the crude calcareous mud or marl (mixed with brine torform a fluid). The resultin products of this ias treatment are carbon dioxide gas. and a 'quor containing calcium chloride, potassium chloride and other soluble salts. The reaction in this step of the method is well-known, as follows:

magnesium oxide, obtained fromthe roas-ting of the magnesium oxychloride, vmixed with potassium chloride obtaine-d from the solar -brine treatment and rening processes described in the applications heretofore refl ferred to. f.,

Themagnesium oxide, together with the potassium chloride and cold fresh water from supply 27 is brought into intimate contact with the carbon dioxide gas. A double salt of potassium and' magnesium carbonate, and magnesium-chloride is thereby formed, according to the following chemical. reaction: i

aMgo axel 4co2 9H2o=2xucoamgco34n2o MgCl2.

The resul-ting,l potassium-magnesium carbonate salt' (KHCOaMgCOZAHZO) is separated from theV adhering magnesium chlo ride liquor, as by centrifuge 28` and'is'then washed with cold water to free it as muchas possible from magnesium chloride. The double salt may then be decomposed by agitation with magnesium oxide and cold water in an agitator 29,-.according to the following chemical re-action: Y

The resulting magnesium carbonate may be separat-ed from the adhering potassium carbonatellquor by centrifuging', at 30 and washing wlth warm water; 'It is then dried and stored at 31 as commercial magnesium` carbonate.

The potassium carbonate liquorfma'y be evaporated for the. production of crude potassium carbonate in an evaporator 32, centrifuged at 33 and stored at34, or it may be treated by well-known means for the'production of caustic potash, or for potassium bicarbonate, or for refined potassium carbonate.

It has been mentioned that the hydro# treatment of the mudand brine by hydrochloric v'acid gas contains original brine yplus the previously water-insoluble, but now water-soluble potassium contents of the mud. rl'his 'calcium-potassium chloride liqucr, ltogether with the'various suspended insoluble impurities contained in the original mud is pumped tothe settling tank 23, where the insoluble material, such as .silica and aluminum oxide, are allowed to settle. The clear liquor which consists essentially of a mixture of calcium chloride and original brine plus the previously insoluble, but

now waterfsoluble potassium chloride ot the mud is then pumped 'to the next succeeding vat or solar pond 24 for evaporation and for,

recovery of potassium chloride'substautially las described in applications Serial Nos.

332,441 and 37 3,183 relativeto treatment' of brines carrying potassium and magnesium chlorides.

The mother liquor from solar pond`24f, consisting essentially of calcium chloride, is then pumpedto storage vat 25and is further concentrated by lsolar evaporation.

`Solar concentration ofthe calcium chloride liquor, therefore, takes place in ponds 23, 24 and 25.

`When sulphates and Ycarbonates are present in the original brine, the calcium chloride liquor from 25 may be employed for precipitating such soluble sul hates and carbonates, forming insoluble' ca -cium sulphate and calcium carbonate and a liquor consisting essentially of chlorides, which liquor maybe treated forthe recovery of potassium and magnesium; IThe calcium sulphate that .is precipitated in vat 35 may be recovered and harvested.

It should be noted that by the use of cali cium chloride liquor as re-agent to precipitate the sulphate of the brine as calcium sulphate, a brine consisting essentially of sodium, potassium and magnesium chlorides is obtained, which can be treated as set forth in the said applicationsand therefore, practically any brine, even those containing considerable sulphate and carbonate may be readily treated by this method.

From the solar concentrated calcium chloride liquor, solid commercial calcium chloride may be obtained by well-known evaporating methods and stored at 36.

Where pure calcium chloride is desired, any

magnesium salts present in the solar concentrated liquor may be precipitated by the addition of calcium h droxide, accordingr to the following well-linown chemical re-acstituted in place of the magnesium oxide herein described as being used in the precipi-A tation ofy magnesium carbonate from the potassium-magnesium carbonate salt.

Having thus described my invention, what I claim and desire' to secure by Letters Patent is:

1. The method of recovering potassium and magnesium salts from natural brine and calcareous muds of substantially the character described, comprising, evaporatiililg the brine by solar heat, removing the res ting sodium and potassium chloride and producing magnesium chloride mother liquor, adding magnesium oxide to saidi vus ' Vcalcareous muds of substantially the charto thereby acter described, comprising, evaporating the brme by solar heat, removin the resulting sodium and potasslum chlori e and producmagnesiuin chloride mother liquor, addmg magnesium oxideto said mother liquor to form a solid, roasting said solid material, produce hydrochloric acid gas and magnesmm oxide, treating a iuid`.m1x

ture .of said mud and brine with hydroprecipitate sulphate therefrom; mixi chloric acid gas, Athereby producing carbon dioxide gas and a residual li ucr containing original brine, potassium ch oride and calcium chloride liquor and insoluble material, settling ,said liquor 4and concentrating the clear residual calcium chloride liquor, adding this clear liquor to the original brine to ma nesium oxide and otassium chlori e axigd water and treatin t e mixture with carbon dioxide gas, there y producing a double salt of potassium and magnesium carbonate and magnesium chloride. Y

3.' The method. of recovering potassium and magnesium salts from; natural brine and material containing carbonate of calcium, comprising evaporating the brine by solar heat, removing the resulting sodium andpotassium chloride Aand -producing magnesium chloride mother'liquor, adding mag'- nesium oxide to said mother liquor to form i a solid, roastin said solid material .tothereby produce hy ochloric acid gas and mag-v nesium oxide, treating said carbonate-containing material and brine with said hydrochloric acid gas, thereby producing carbon dioxidev gas, mixing magnesium oxide and potassium chloride and water and treating the mixture with carbon dioxide gas, thereby producing a' double salt of potassium and Ingnesium carbonate and magnesium chlor1 e.

4. The method of recovering potassium 'and magnesium salts from brine and a carbonate-bearing material, comprising evaporating the brine, removing the resulting salts and producing a more concentrated.

liquor consisting essentially of magnesium chloride and Water, addingmagnesium oxide to said concentrated liquor to form a solid, roasting said solid material to thereby produce hydrochloric acid gas and magnesium oxide, treating said carbonate-bearing material, with said hydrochloric acid gas, thereby producing carbon dioxide gas,

mixinnr magnesium oxide and potassium chloride and water, treating the mixture With carbon dioxide gas, thereby producing a double salt of potassium and magnesium carbonate and magnesium chloride:

5. The method of recovering potassium and magnesium salts from brine and material containing carbonate of calcium comprising evaporating the brine and producing a concentrated liquor consisting essentially of magnesium chloride and water, adding magnesium oxide to said concentrated liquor to forma solid, roasting said solid to thereby produce hydrochloric acid gas and magnesium oxide, treating said carbanale-bearing material with said hydrochloric gas t ereby producing carbon dioxide gas and a liquor containing calcium chloride, adding a portion of said calcium chloride liquor to the orignal brine to precipitate any soluble sulphate thereby producing a liquor practically phate, evaporating-said liquor for the pro duction of potassium chloride and magnesium chloride; mixin said magnesium voxide with potassium c loride and water and treating the mixture with said carbon dioxide gas, therebyt producing a double salt of potassium and magnesium carbonate; evaporating the remainderof -said calciumV chloride liquor for the production of calcium chloride.

In testimony whereof, I aiix my signature in presence of two witnesses.

- JOS-EPH L. SILSBEE. Witnesses:

B.. D. SEYMOUR, H. R. Trroms.

ree from sul- 

